net.sf.saxon.expr.instruct

## Class NamespaceConstructor

- java.lang.Object
- - net.sf.saxon.expr.Expression
  - - net.sf.saxon.expr.instruct.Instruction
    - - net.sf.saxon.expr.instruct.SimpleNodeConstructor
      - - net.sf.saxon.expr.instruct.NamespaceConstructor

- All Implemented Interfaces:
    Serializable, SourceLocator, LocationProvider, SaxonLocator, TailCallReturner, InstructionInfo, Locator

      public class NamespaceConstructor
      extends SimpleNodeConstructor

  A namespace constructor instruction. (xsl:namespace in XSLT 2.0, or namespace{}{} in XQuery 1.1)
  See Also:
    Serialized Form

- - ### Field Summary

    - ### Fields inherited from class net.sf.saxon.expr.instruct.SimpleNodeConstructor

      `select`

    - ### Fields inherited from class net.sf.saxon.expr.Expression

      `EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, INHERITED_CONTEXT, INSPECTION_CONTEXT, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, NAVIGATION_CONTEXT, NODE_VALUE_CONTEXT, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, W3C_CONSUMING, W3C_FREE_RANGING, W3C_GROUP_CONSUMING, W3C_MOTIONLESS, WATCH_METHOD`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `NamespaceConstructor(Expression name)` Create an xsl:namespace instruction for dynamic construction of namespace nodes

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `Expression` | `copy()` Copy an expression.
    `NodeInfo` | `evaluateItem(XPathContext context)` Evaluate as an expression.
    `NodeName` | `evaluateNodeName(XPathContext context)` Run-time method to compute the name of the node being constructed.
    `void` | `explain(ExpressionPresenter out)` Diagnostic print of expression structure.
    `int` | `getCardinality()` Determine the static cardinality of the expression.
    `ExpressionCompiler` | `getExpressionCompiler()` Return the compiler of the NamespaceConstructor expression
    `int` | `getInstructionNameCode()` Set the name of this instruction for diagnostic and tracing purposes
    `ItemType` | `getItemType(TypeHierarchy th)` Get the item type of the items returned by evaluating this instruction
    `Expression` | `getNameExpression()` Get the expression that defines the namespace node's name
    `Iterator<SubExpressionInfo>` | `iterateSubExpressionInfo()` Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
    `Iterator<Expression>` | `iterateSubExpressions()` Get the immediate sub-expressions of this expression.
    `void` | `localTypeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)` Method to perform type-checking specific to the kind of instruction
    `void` | `processValue(CharSequence value, XPathContext context)` Process the value of the node, to create the new node.
    `protected void` | `promoteInst(PromotionOffer offer)` Offer promotion for subexpressions.
    `boolean` | `replaceSubExpression(Expression original, Expression replacement)` Replace one subexpression by a replacement subexpression
    `Expression` | `simplify(ExpressionVisitor visitor)` Simplify an expression.

    - ### Methods inherited from class net.sf.saxon.expr.instruct.SimpleNodeConstructor

      `checkContent, computeCardinality, computeSpecialProperties, createsNewNodes, getContentExpression, getStreamingAdjunct, iterate, optimize, processLeavingTail, setSelect, typeCheck`

    - ### Methods inherited from class net.sf.saxon.expr.instruct.Instruction

      `assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getExpressionName, getImplementationMethod, getInstructionName, getIteratorFromProcessMethod, getSourceLocator, isXSLT, process, promote`

    - ### Methods inherited from class net.sf.saxon.expr.Expression

      `addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getColumnNumber, getColumnNumber, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getSystemId, getSystemId, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, toString, typeError`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface javax.xml.transform.SourceLocator

      `getColumnNumber, getLineNumber, getPublicId, getSystemId`

- - ### Constructor Detail

    - #### NamespaceConstructor

          public NamespaceConstructor(Expression name)

      Create an xsl:namespace instruction for dynamic construction of namespace nodes
      Parameters:
        `name` - the expression to evaluate the name of the node (that is, the prefix)

  - ### Method Detail

    - #### getNameExpression

          public Expression getNameExpression()

      Get the expression that defines the namespace node's name
      Returns:
        the expression that defines the namespace node's name (that is, the namespace prefix)

    - #### getInstructionNameCode

          public int getInstructionNameCode()

      Set the name of this instruction for diagnostic and tracing purposes
      Overrides:
        `getInstructionNameCode` in class `Instruction`
      Returns:
        a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace

    - #### simplify

          public Expression simplify(ExpressionVisitor visitor)
                              throws XPathException

      Description copied from class: `Instruction`
      Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.
      Overrides:
        `simplify` in class `SimpleNodeConstructor`
      Parameters:
        `visitor` - an expression visitor
      Returns:
        the simplified expression
      Throws:
        `XPathException` - if an error is discovered during expression rewriting

    - #### getItemType

          public ItemType getItemType(TypeHierarchy th)

      Description copied from class: `Instruction`
      Get the item type of the items returned by evaluating this instruction
      Overrides:
        `getItemType` in class `Instruction`
      Parameters:
        `th` - the type hierarchy cache
      Returns:
        the static item type of the instruction

    - #### getCardinality

          public int getCardinality()

      Description copied from class: `Expression`
      Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.
      Overrides:
        `getCardinality` in class `Expression`
      Returns:
        one of the values Cardinality.ONE_OR_MORE, Cardinality.ZERO_OR_MORE, Cardinality.EXACTLY_ONE, Cardinality.ZERO_OR_ONE, Cardinality.EMPTY. This default implementation returns ZERO_OR_MORE (which effectively gives no information).

    - #### promoteInst

          protected void promoteInst(PromotionOffer offer)
                              throws XPathException

      Description copied from class: `SimpleNodeConstructor`
      Offer promotion for subexpressions. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.
      Overrides:
        `promoteInst` in class `SimpleNodeConstructor`
      Parameters:
        `offer` - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression
      Throws:
        `XPathException` - if any error is detected

    - #### localTypeCheck

          public void localTypeCheck(ExpressionVisitor visitor,
                            ExpressionVisitor.ContextItemType contextItemType)
                              throws XPathException

      Description copied from class: `SimpleNodeConstructor`
      Method to perform type-checking specific to the kind of instruction
      Specified by:
        `localTypeCheck` in class `SimpleNodeConstructor`
      Parameters:
        `visitor` - an expression visitor
        `contextItemType` - the static type of the context item
      Throws:
        `XPathException` - if a type error is detected

    - #### iterateSubExpressions

          public Iterator<Expression> iterateSubExpressions()

      Description copied from class: `Expression`
      Get the immediate sub-expressions of this expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.
      Overrides:
        `iterateSubExpressions` in class `SimpleNodeConstructor`
      Returns:
        an iterator containing the sub-expressions of this expression

    - #### iterateSubExpressionInfo

          public Iterator<SubExpressionInfo> iterateSubExpressionInfo()

      Description copied from class: `SimpleNodeConstructor`
      Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.
      Overrides:
        `iterateSubExpressionInfo` in class `SimpleNodeConstructor`
      Returns:
        an iterator containing the sub-expressions of this expression

    - #### copy

          public Expression copy()

      Copy an expression. This makes a deep copy.
      Specified by:
        `copy` in class `Expression`
      Returns:
        the copy of the original expression

    - #### replaceSubExpression

          public boolean replaceSubExpression(Expression original,
                                     Expression replacement)

      Replace one subexpression by a replacement subexpression
      Overrides:
        `replaceSubExpression` in class `SimpleNodeConstructor`
      Parameters:
        `original` - the original subexpression
        `replacement` - the replacement subexpression
      Returns:
        true if the original subexpression is found

    - #### evaluateNodeName

          public NodeName evaluateNodeName(XPathContext context)
                                    throws XPathException

      Description copied from class: `SimpleNodeConstructor`
      Run-time method to compute the name of the node being constructed. This is overridden for nodes that have a name. The default implementation returns -1, which is suitable for unnamed nodes such as comments
      Overrides:
        `evaluateNodeName` in class `SimpleNodeConstructor`
      Parameters:
        `context` - the XPath dynamic evaluation context
      Returns:
        the name pool nameCode identifying the name of the constructed node
      Throws:
        `XPathException` - if any failure occurs

    - #### processValue

          public void processValue(CharSequence value,
                          XPathContext context)
                            throws XPathException

      Description copied from class: `SimpleNodeConstructor`
      Process the value of the node, to create the new node.
      Specified by:
        `processValue` in class `SimpleNodeConstructor`
      Parameters:
        `value` - the string value of the new node
        `context` - the dynamic evaluation context
      Throws:
        `XPathException` - if a dynamic error occurs

    - #### evaluateItem

          public NodeInfo evaluateItem(XPathContext context)
                                throws XPathException

      Evaluate as an expression. We rely on the fact that when these instructions are generated by XQuery, there will always be a valueExpression to evaluate the content
      Overrides:
        `evaluateItem` in class `SimpleNodeConstructor`
      Parameters:
        `context` - The context in which the expression is to be evaluated
      Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
      Throws:
        `XPathException` - if any dynamic error occurs evaluating the expression

    - #### getExpressionCompiler

          public ExpressionCompiler getExpressionCompiler()

      Return the compiler of the NamespaceConstructor expression
      Overrides:
        `getExpressionCompiler` in class `Expression`
      Returns:
        the relevant ExpressionCompiler

    - #### explain

          public void explain(ExpressionPresenter out)

      Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
      Specified by:
        `explain` in class `Expression`
      Parameters:
        `out` - the expression presenter used to display the structure

Copyright (c) 2004-2013 Saxonica Limited. All rights reserved.